Miguel Farias of Coventry University on why mindfulness and other types of meditation can sometimes leave people worse off:

Sometimes when people are trying to still their thoughts, the mind can “rebel.” “It’s like a backlash to the attempt to control the mind, and this results in an episode of anxiety or depression.” This doesn’t mean people should stop trying the technique, but instead should opt for guided meditation sessions, led by a teacher or an app with a recorded narration.